DIY 5E3 high pitched squeal...

...when the bright channel volume OR the tone control is dimed. The guitar is not even plugged in. The normal channel doesn't do it. Changed all tubes...still squeals. It has to be one of the two tone control caps...right?

Any suggestions welcome.

sure it isn't a cap...
1.- just bad lead dress....
2.- or you need to interchange the brown and blue cables going from the 6V6 to the Output Transformer

Check the jacks on the bright channel. Sometimes the switching jack can get a little bent and not close when the guitar's unplugged.

Stock layout or totally DIY?

If you have miles and miles of wire between the PI coupling caps and the power tube grids it's gonna squeal.

Switching OT leads does very little on a tweed Deluxe. No NFB, remember?

IF it is a Fender 5E3 Deluxe Clone It shouldn´t have negative feedback, BUT it shouldn´t have a bright channel either so the question is:What have you built?Personally,I have never liked the kind of tone control the 5E3 has.I find it impossible to find setting a setting that I like.

IF it is a Fender 5E3 Deluxe Clone It shouldn´t have negative feedback, BUT it shouldn´t have a bright channel either so the question is:What have you built?

That's odd. That's odd because every repro 5E3 chassis has two channels, "normal" and "bright".

Personally,I have never liked the kind of tone control the 5E3 has.I find it impossible to find setting a setting that I like.

Then your guitar is your problem not your amp.

My "normal" channel does a tone similar to a pre-War Martin. Part of it is the amp, part of it is the guitar. A custom Tele with Fralins is a big part of it. It's not my favorite guitar for the "bright" channel.

It's a matter of voicing the amp to taste. I can tweak my tone control so it's more like a treble control, all it does it take a bit of the edge off the bridge pickup. I treat it like it's there to compensate for different guitars. It's not a dramatic tone shaper.

Check the jacks on the bright channel. Sometimes the switching jack can get a little bent and not close when the guitar's unplugged.

cousinpaul!

You hit it right on the head, sir. One of the input jacks was not making good contact with the switch part of the jack when nothing plugged in there. I guess it wasn't a problem when I gigged with it last time because I was plugging my geetar into that port. (?)

Anyway, I owe you lunch.:grin: